/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.session;

import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.Manager;
import org.apache.catalina.Store;
import org.apache.catalina.util.CustomObjectInputStream;
import org.apache.catalina.util.LifecycleBase;
import org.apache.tomcat.util.res.StringManager;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;

/**
 * Abstract implementation of the {@link Store} interface to
 * support most of the functionality required by a {@link Store}.
 *
 * @author Bip Thelin
 */
public abstract class StoreBase extends LifecycleBase implements Store {

	// ----------------------------------------------------- Instance Variables

	/**
	 * The descriptive information about this implementation.
	 */
	protected static final String info = "StoreBase/1.0";
	/**
	 * The string manager for this package.
	 */
	protected static final StringManager sm = StringManager.getManager(StoreBase.class);
	/**
	 * Name to register for this Store, used for logging.
	 */
	protected static String storeName = "StoreBase";
	/**
	 * The property change support for this component.
	 */
	protected PropertyChangeSupport support = new PropertyChangeSupport(this);
	/**
	 * The Manager with which this Store is associated.
	 */
	protected Manager manager;

	// ------------------------------------------------------------- Properties

	/**
	 * @return the info for this Store.
	 */
	@Override
	public String getInfo() {
		return info;
	}

	/**
	 * @return the name for this Store, used for logging.
	 */
	public String getStoreName() {
		return storeName;
	}

	/**
	 * @return the Manager with which the Store is associated.
	 */
	@Override
	public Manager getManager() {
		return this.manager;
	}

	/**
	 * Set the Manager with which this Store is associated.
	 *
	 * @param manager The newly associated Manager
	 */
	@Override
	public void setManager(Manager manager) {
		Manager oldManager = this.manager;
		this.manager = manager;
		support.firePropertyChange("manager", oldManager, this.manager);
	}


	// --------------------------------------------------------- Public Methods

	/**
	 * Add a property change listener to this component.
	 *
	 * @param listener a value of type {@link PropertyChangeListener}
	 */
	@Override
	public void addPropertyChangeListener(PropertyChangeListener listener) {
		support.addPropertyChangeListener(listener);
	}

	/**
	 * Remove a property change listener from this component.
	 *
	 * @param listener The listener to remove
	 */
	@Override
	public void removePropertyChangeListener(PropertyChangeListener listener) {
		support.removePropertyChangeListener(listener);
	}

	/**
	 * Get only those keys of sessions, that are saved in the Store and are to
	 * be expired.
	 *
	 * @return list of session keys, that are to be expired
	 * @throws IOException if an input-/output error occurred
	 */
	public String[] expiredKeys() throws IOException {
		return keys();
	}

	/**
	 * Called by our background reaper thread to check if Sessions
	 * saved in our store are subject of being expired. If so expire
	 * the Session and remove it from the Store.
	 */
	public void processExpires() {
		String[] keys = null;

		if (!getState().isAvailable()) {
			return;
		}

		try {
			keys = expiredKeys();
		} catch (IOException e) {
			manager.getContainer().getLogger().error("Error getting keys", e);
			return;
		}
		if (manager.getContainer().getLogger().isDebugEnabled()) {
			manager.getContainer().getLogger().debug(getStoreName() + ": processExpires check number of " + keys.length + " sessions");
		}

		long timeNow = System.currentTimeMillis();

		for (int i = 0; i < keys.length; i++) {
			try {
				StandardSession session = (StandardSession) load(keys[i]);
				if (session == null) {
					continue;
				}
				int timeIdle = (int) ((timeNow - session.getThisAccessedTime()) / 1000L);
				if (timeIdle < session.getMaxInactiveInterval()) {
					continue;
				}
				if (manager.getContainer().getLogger().isDebugEnabled()) {
					manager.getContainer().getLogger().debug(getStoreName() + ": processExpires expire store session " + keys[i]);
				}
				boolean isLoaded = false;
				if (manager instanceof PersistentManagerBase) {
					isLoaded = ((PersistentManagerBase) manager).isLoaded(keys[i]);
				} else {
					try {
						if (manager.findSession(keys[i]) != null) {
							isLoaded = true;
						}
					} catch (IOException ioe) {
						// Ignore - session will be expired
					}
				}
				if (isLoaded) {
					// recycle old backup session
					session.recycle();
				} else {
					// expire swapped out session
					session.expire();
				}
				remove(keys[i]);
			} catch (Exception e) {
				manager.getContainer().getLogger().error("Session: " + keys[i] + "; ", e);
				try {
					remove(keys[i]);
				} catch (IOException e2) {
					manager.getContainer().getLogger().error("Error removing key", e2);
				}
			}
		}
	}


	// --------------------------------------------------------- Protected Methods

	/**
	 * Create the object input stream to use to read a session from the store.
	 * Sub-classes <b>must</b> have set the thread context class loader before
	 * calling this method.
	 *
	 * @param is The input stream provided by the sub-class that will provide
	 *           the data for a session
	 * @return An appropriately configured ObjectInputStream from which the
	 * session can be read.
	 * @throws IOException if a problem occurs creating the ObjectInputStream
	 */
	protected ObjectInputStream getObjectInputStream(InputStream is) throws IOException {
		BufferedInputStream bis = new BufferedInputStream(is);

		CustomObjectInputStream ois;
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

		if (manager instanceof ManagerBase) {
			ManagerBase managerBase = (ManagerBase) manager;
			ois = new CustomObjectInputStream(bis, classLoader, manager.getContainer().getLogger(),
					managerBase.getSessionAttributeValueClassNamePattern(),
					managerBase.getWarnOnSessionAttributeFilterFailure());
		} else {
			ois = new CustomObjectInputStream(bis, classLoader);
		}

		return ois;
	}

	@Override
	protected void initInternal() {
		// NOOP
	}

	/**
	 * Start this component and implement the requirements
	 * of {@link LifecycleBase#startInternal()}.
	 *
	 * @throws LifecycleException if this component detects a fatal error
	 *                            that prevents this component from being used
	 */
	@Override
	protected synchronized void startInternal() throws LifecycleException {

		setState(LifecycleState.STARTING);
	}

	/**
	 * Stop this component and implement the requirements
	 * of {@link LifecycleBase#stopInternal()}.
	 *
	 * @throws LifecycleException if this component detects a fatal error
	 *                            that prevents this component from being used
	 */
	@Override
	protected synchronized void stopInternal() throws LifecycleException {

		setState(LifecycleState.STOPPING);
	}

	@Override
	protected void destroyInternal() {
		// NOOP
	}

	/**
	 * @return a String rendering of this object.
	 */
	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder(this.getClass().getName());
		sb.append('[');
		if (manager == null) {
			sb.append("Manager is null");
		} else {
			sb.append(manager);
		}
		sb.append(']');
		return sb.toString();
	}
}
